Muscle blood flow in children, measured by 133Xe clearance method.

Resting and maximal values of blood flow through limb muscles are higher in children than in adults; on the contrary, the time necessary for reaching maximal blood flow and the latter's duration are shorter. Simultaneous measurements in both upper or in both lower limbs, and in the right upper and right lower limbs, revealed no statistically significant differences among the values.     

Changes in blood flow of growing experimental tumor determined by the clearance of 133Xe

133Xe clearance method has been employed for measurement of the blood flow in 6C3HED lymphosarcoma implanted in flank of C3H mice. In small tumors (9-day old) the mean rate of blood flow was 9.4 +/- 5.0 ml/100g/min. but with progressing growth of tumors the rate of blood flow significantly decreased. In large tumors (14-day old) the mean rate of the blood flow was only 5.4 +/- 2.8. Our results demonstrate that this type of tumor, similarly as most of transplanted tumors are not well perfused and, that there is an inverse relationhip between the blood flow and the tumor size.     

Clinical study of liver blood flow in man measured by 133Xe clearance after portal vein injection.

During the course of a clinical trial to assess the value of adjuvant liver perfusion of 5-fluorouracil after surgery for colorectal cancer, liver blood flow was measured in 14 patients. Access to the portal circulation was achieved by dilatation and cannulation of the obliterated umbilical vein. The clearance from the liver of a bolus of 133Xe was monitored using a gamma-ray camera so that blood flow from different areas of the liver could be calculated. The clearance curve of 133Xe was a double exponential of which the initial fast component accounted for a consistently high proportion of the total clearance. The perfusion studies have shown wide differences in blood flow to the various areas of the liver in the same patient, in addition to a wide variation in perfusion rate between the 14 patients. This technique of quantitative estimations of liver blood flow to different areas of the liver may have importance in planning operative procedures and understanding the haemodynamic mechanisms involved in liver disease.     

Clinical value of the study of myocardial blood flow by the method of Xe133 clearance in ischemic heart disease]

The clearance of intracoronarily introduced 133Xe was employed in investigating the myocardial blood flow in 105 patients, 10 of whom--controls and 95 suffering from various manifestations of ischemic heart disease. Use was made of the biexponential calculation of the clearance curve by taking account of the fast (circulation in normal tissues) and slow exponent (circulation along the cicatricially-altered sections of the myocardium) contributions to the common "effective" myocardial blood flow. In patients with ischemic heart disease a reduction of the myocardial blood flow depending upon the severity of the clinical picture and the degree of the coronary arteries lesion was revealed. A direct correlational dependence between the initial state of the myocardial circulation at rest and the level of the physical efforts tolerance was educed. A conclusion is drawn that the determination of the myocardial circulation by the method of the 133Xe clearance following intracoronarily administration of the substance should be done by taking account of the slow and fast exponents of the clearance curve, these exponents reflecting the circulation in sections of the myocardium differing in their functional activity.     

Blood flow in liver tumors--effects of vasoactive drugs estimated with xenon (133Xe) clearance

BACKGROUND/AIMS: The aim of the present study was to identify in a standardized experimental rat liver tumor system the drugs which are most appropriate in influencing the relationship between liver tumor and normal liver parenchyma blood flow as estimated with 133Xe washout clearance method, and thereby positively influencing the kinetics of chemotherapeutic drugs. A battery of vasoactive drugs, which according to a literature review were considered to be active, were tested. METHODOLOGY: Twelve drugs were administered intravenously on 113 Wistar-Fu rats with an experimental adenocarcinoma in the liver (weight 0.62 g). 133Xe was applied in the tumor and in normal parenchyma with and without administration of a vasoactive drug. The pulses were registered with a NaI (Tl)-scintillation detector connected to a multichannel analyzer. The disappearance rate of the isotope was calculated according to a single compartment model. Four recordings were performed in each rat randomly in tumor and liver parenchyma with and without a drug (series A) and one series twice in tumor and twice in parenchyma with a drug (series B). RESULTS: In unaffected animals the tumor to liver quotient was 0.57+/-0.35. This quotient was higher in tumors less than 0.53 g. Angiotensin-II 8 mg i.v. increased the quotient to 0.95+/-0.20. No other drug significantly influenced the quotient. CONCLUSIONS: In an experimental adenocarcinoma in the liver this study has investigated the possibility of increasing the tumor to normal liver parenchyma blood flow quotient by a variety of vasoactive substances for the beneficial modification of tumor blood flow. Angiotensin II 8 mg i.v. was the only drug, which increased the quotient. None of the other tested drugs were supporting previous presented results on influencing tumor blood flow.     

TCD与~(133)Xe吸入法对老年脑梗塞者脑血流量的测定

目的研究老年脑梗塞患者脑血流动力学及脑血流量（ＣＢＦ）。方法随机选择７３例老年及５０例非老年患者，同时做ＴＣＤ及１３３Ｘｅ吸入法测定ＣＢＦ。结果发现老年组患者ＴＣＤ主要表现为病灶区血流速度降低，共６３例，占８６．３％；非老年组则为２３例，占４６．０％，２组比较，Ｐ＜０．０１；２组血流速度降低均与相应ＣＢＦ降低呈正相关，在老年组ｒ＝０．９４，Ｐ＜０．０１，非老年组ｒ＝０．８８，Ｐ＜０．０１；脑梗塞病灶大则血流速度、ＣＢＦ降低者多。结论老年脑梗塞患者血流速度降低与脑血流量减少有良好的一致性，ＴＣＤ可作为评价ＣＢＦ的有效手段。     

Effect of aging on hepatic clearance of vasopressin in Fischer 344 rats

The effect of aging on vasopressin (VP) clearance was studied in male Fischer 344 rats 2 (young), 12 (adult) and 30 (old) months of age using in situ liver perfusion technique. The liver was perfused with Krebs-Henseleit bicarbonate buffer containing 1% bovine serum albumin and VP (2 ng/ml), at a constant temperature of 37 +/- 0.5 degrees C and a flow rate of 150 ml/h for 120 min. Expressed per whole liver and per gram tissue, VP declined exponentially over the studied period fitting well to the curve y = bekx (p = 0.0001) in all three groups. The analysis of covariance revealed the slope of the VP decay curve to be steepest in old rats, significantly different from that of young (p = 0.0001 expressed per whole liver or per gram tissue) and adult (p = 0.0001 and p = 0.001, expressed per whole liver and per gram tissue, respectively) rats. This suggests that, at least in male Fischer 344 rats, the hepatic clearance of VP was fastest in old rats.     

Use of dipyridamole and the radioactive 133Xe clearance method for assessing the coronary reserve of stenocardia patients

Coronary flow reserve was assessed by means of the 133Xe clearance test making use of dipyridamole in the left coronary artery of 11 patients with angina of effort and coronary arterial stenoses involving also the basin of the left coronary artery (group 1), 6 patients with the anginal syndrome showing no angiographic evidence of coronary lesions (group 2A), and 6 patients with cardialgias and intact coronarograms (group 2B). Coronary reserve was shown to be decreased in groups 1 and 2A, as compared to the values shown by group 2B patients.     

Effect of vasopressin on phasic coronary blood flow

Summary The effects of vasopressin on the coronary circulation have been studied with regard to its general hemodynamic effects. Aortic blood pressure (BP), left ventricular pressure (LVP), aortic blood flow (AoBF), and circumflex blood flow (CBF), were measured in 12 open-chest dogs, under control conditions and during vasopressin infusion (25 mU/kg/min). During vasopressin infusion, the mean aortic blood pressure (MBP) was increased from 104±23 mm Hg to 161±23 mm Hg. The diastolic blood pressure (DBP) was more increased (+55%) than the systolic blood pressure (SBP) (+40%). AoBF was decreased from 2.169±0.408 l/min to 1.118±0.303 l/min; and the heart rate was decreased by 18%. The total combined left ventricular power did not change significantly. The increase in total peripheral resistance (TPR) (+200%) was the main change in impedance spectrum. The mean circumflex coronary blood flow (MCBF) was decreased from 48±8.6 ml/min to 33.4±9.7 ml/min. This decrease was more important in the diastolic circumflex blood flow (DCBF) (–33%) than in the systolic one (–0.8%). The diastolic pressure time index (DPTI) was more increased than the systolic pressure time index (SPTI). The DPTI/SPTI ratio was increased from 0.91 to 1.3.Long diastoles, induced by vagus nerve stimulation, have permitted to characterise the relationship between pressure and coronary blood flow during diastole. This relationship was linear under basal condition, and during vasopressin perfusion. This made it possible to determine the critical closing pressure (Pf0), and the coronary conductance (the slope of the regression curve). Vasopressin induced an increase in Pf0, from 33.7±95 to 77.4±16.07 mm Hg (p<0.001), and a decrease in coronary conductance, from 0.8±0.32 to 0.5±0.1 ml/min/mm Hg. The effect of an acute change in perfusion pressure on the coronary flow, under control conditions and during vasopressin infusion was studied by opening a large arteriovenous fistula. Unclamping of the fistula, under control conditions, allowed to realize an acute fall in DBP from 82.5±6.36 to 35.5±9.19 mm Hg, and in DCBF, from 58.5±9.2 to 20±9.8 ml/min. During vasopressin infusion, a similar fall in perfusion pressure lead to a zero diastolic circumflex blood flow, for a diastolic aortic blood pressure of 56±12 mm Hg. However, vasopressin did not affect the delayed active coronary vasodilatation.     

Effect of somatostatin on 133Xe clearance from colonic mucosa before and after local nervous blockade in unanaesthetized man

The effect of intravenous somatostatin bolus on mucosal and submucosal blood flow in six patients with colostomies was studied with the local 133Xe clearance technique. Mucosal and submucosal blood flow decreased by 28% after somatostatin injection. After induction of local nervous blockade by infiltrating the labelled area of the mucosal membrane with lidocaine the reduction in blood flow caused by somatostatin was abolished. These observations suggest that the vasoconstrictor effect of somatostatin is mediated by neurogenic mechanisms.